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- /*=============================================================================
- Copyright (c) 2002-2003 Joel de Guzman
- http://spirit.sourceforge.net/
- Use, modification and distribution is subject to the Boost Software
- License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- http://www.boost.org/LICENSE_1_0.txt)
- =============================================================================*/
- ///////////////////////////////////////////////////////////////////////////////
- //
- // This calculator example demontrates the use of subrules.
- // This is discussed in the "Subrule" chapter in the Spirit User's Guide.
- //
- // [ JDG 4/11/2002 ]
- //
- ///////////////////////////////////////////////////////////////////////////////
- //#define BOOST_SPIRIT_DEBUG // define this for debug output
- #include <boost/spirit/include/classic_core.hpp>
- #include <iostream>
- #include <string>
- using namespace std;
- using namespace BOOST_SPIRIT_CLASSIC_NS;
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Semantic actions
- //
- ///////////////////////////////////////////////////////////////////////////////
- namespace
- {
- void do_int(char const* str, char const* end)
- {
- string s(str, end);
- cout << "PUSH(" << s << ')' << endl;
- }
- void do_add(char const*, char const*) { cout << "ADD\n"; }
- void do_subt(char const*, char const*) { cout << "SUBTRACT\n"; }
- void do_mult(char const*, char const*) { cout << "MULTIPLY\n"; }
- void do_div(char const*, char const*) { cout << "DIVIDE\n"; }
- void do_neg(char const*, char const*) { cout << "NEGATE\n"; }
- }
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Our calculator grammar (using subrules)
- //
- ///////////////////////////////////////////////////////////////////////////////
- struct calculator : public grammar<calculator>
- {
- template <typename ScannerT>
- struct definition {
- definition(calculator const& /*self*/)
- {
- first = (
- expression =
- term
- >> *( ('+' >> term)[&do_add]
- | ('-' >> term)[&do_subt]
- )
- ,
- term =
- factor
- >> *( ('*' >> factor)[&do_mult]
- | ('/' >> factor)[&do_div]
- )
- ,
- factor
- = lexeme_d[(+digit_p)[&do_int]]
- | '(' >> expression >> ')'
- | ('-' >> factor)[&do_neg]
- | ('+' >> factor)
- );
- BOOST_SPIRIT_DEBUG_NODE(first);
- BOOST_SPIRIT_DEBUG_NODE(expression);
- BOOST_SPIRIT_DEBUG_NODE(term);
- BOOST_SPIRIT_DEBUG_NODE(factor);
- }
- subrule<0> expression;
- subrule<1> term;
- subrule<2> factor;
- rule<ScannerT> first;
- rule<ScannerT> const&
- start() const { return first; }
- };
- };
- ///////////////////////////////////////////////////////////////////////////////
- //
- // Main program
- //
- ///////////////////////////////////////////////////////////////////////////////
- int
- main()
- {
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "\t\tA calculator using subrules...\n\n";
- cout << "/////////////////////////////////////////////////////////\n\n";
- cout << "Type an expression...or [q or Q] to quit\n\n";
- calculator calc; // Our parser
- string str;
- while (getline(cin, str))
- {
- if (str.empty() || str[0] == 'q' || str[0] == 'Q')
- break;
- parse_info<> info = parse(str.c_str(), calc, space_p);
- if (info.full)
- {
- cout << "-------------------------\n";
- cout << "Parsing succeeded\n";
- cout << "-------------------------\n";
- }
- else
- {
- cout << "-------------------------\n";
- cout << "Parsing failed\n";
- cout << "stopped at: \": " << info.stop << "\"\n";
- cout << "-------------------------\n";
- }
- }
- cout << "Bye... :-) \n\n";
- return 0;
- }
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